Prop for 700-800hp Rage
 

Using a cupped 30 Bravo 4 and hitting the rev guard hard at 5450 @ 93mph. Thinking it may be time for a 32? Not sure where to go, any suggestions. Power from a whippled 496 with forged internals, CMI headers and 7lbs of boost. Thanks.
BTW this was my first day @ 7lbs of boost......WOW! :evilb::evilb::evilb::evilb:

Can you get the rev limiter raised? If so, I would have it raised to 5800. Is the 30 stock? If so add about .020 cup, no more. The 32 takes a lot of work to get them to hook up right. Never seen 2 of them run the same. They have a good amount of slip.

Raising your limiter should also give you another pound of boost, and horsepower comes with boost. With forged internals you should be OK @ 5800/5900. I wouldn't run it there all day, but for occaisional blasts, it's OK.
A 30" P5-X or Herring 5 blade (really are 30" pitch, and the extra blade will pull Rs down some too, with more efficient slip #s) would be a good test if you can find one, or a 32" B1 with cupping similar to your 30".
Sounds like you have your boat dialed in nicely. Congrats.
Steve

Somewhere the math is off...
at 29 pitch.. which is what a 30 is stock.. slip is at 6.7%
at 30 pitch .. slip is at a little over 9%

It is hard to believe that a Bravo prop has slip that low ... Hmmm

Anyway... I agree with Steve... demo a Hydromotive 30 P5x. Hydromotive has a demo program. Going up 1 inch in the hydromotives pitch will reduce rpm aproximately 150-170 rpm.

That is my favorite all-around prop.

I regularly spin a labbed 30 p5x at 5600 rpm to 92.8 mph which equals about 12.2% slip

Sounds like your boat is running pretty darn good.


Chris

Read the post for prop ~600 hp rage. I run approx same 750 hp (whipple 500EFI) & turn a 32 labbed 5400ish & 90ish. My prop slip calcs are around 17-18%. Slip drops with my labbed 28 to about 15-16% on the 5750 limiter @ 84mph. 32 labbed should be what you need. I don't see how 93 is possible with that prop & that rpm. Desert Rage & I have compared/tried many props with comparable hp & consistent results.

As I said... the math doesn't add up.

Either the GPS is wrong, or the tach is off (which is quite often the case), or this is a fuzzy number for speed.

Something doesn't add up.

I am glad the boat is running well though, and that you are having fun... that is what it all about in the end.

Chris

I do see where you hitting the rev limiter at 5450 so the tach seems right I suppose.
However I don't recall any mention of this detail ; Is this with a GPS speedo?
:party-smiley-004:

A non-GPS speedo would make sense.

Chris

He said the 30" prop was cupped. It's possible to knock a couple of hundred rpm off with heavy cupping, so that could skew the slip numbers quite a bit.

The 496 whipple moter I built for 22 Daytona made peak HP at 5500 RPM. That was with a Raylar blower cam. The stock cam would probably peak sooner. The 496's don't seem to like a lot of rpm like a 502 based engine does. I'd try to prop for no more than 5500 unless you have dyno numbers telling you otherwise.

That could make sense also... but... that seems awful fast for his engine setup in a Rage.

Chris

You would be correct. The prop was cupped to bring my revs down 200. Unlike others who have labbed their props to bring their rpm number higher. Next I'll be hearing that 28's are faster than 25's with similar power.

Yup.. the prop cupping makes sense.. just seems pretty darn fast for a Rage with that amound of power... on the other hand.. the other two guys on here that have been commenting do live at a higher elevation.

I don't think that anyone thinks that 28's and 25's are the same speed given the same horsepower. The smaller/lighter Rage will be faster and quicker... unless the water gets rough, and then the bigger boat will do better.

The fastest single engine v-hull that I have personally seen, was a Rage with a twin-turbo motor in it, here on one of the local lakes. It did 115 mph if I remember correctly.

Chris

We do live higher (4500') but have run here & Havasu. I have 2 props for different altitudes. Most lakes around here are 6000'. I need an in between for Utah lake & Powell. I've recently rebuilt my 500 Whipple so haven't had a chance to test down there but my previous trips & Jon's (Desert Rage) recent trip with his 650+hp & turning my 32 merc lab @ Mohave got slightly slower results than this. He also ran a local labbed 28 down there & much slower, same revs. The cup may make some difference, but those slip #'s are cat kind of slip #, but if it works, more power to ya! Maybe we all need to add some more cup. Kinda like drag racing, power doesn't matter if you can't get it to the ground (water)

Jon actually took my 30 down to Mohave which runs exactly stock 30 numbers.
I believe he turned it right near 5500 and 86 mph (correct me if I'm wrong Jon) so cupping to get 7 mph is pure magic :cool-smiley-011:

Still looking for the answer to the GPS speedo question :party-smiley-004:

That's right, at Mohave over Halloween I could hit 89.5 gps @ 5500 with 90MPHrage's Merc Labbed 32 and 86 @ 5400 with Dave's locally labbed 30. Elevation is aroung 620' and air temp was a wonderful 85.

5400 @ 86 mph is almost 16% slip. Every stock prop I've run on a Rage is right at 13% slip. So, your worked prop seems a little on the high side. 13% slip would put a 30 at 89+ MPH, now add 1" pitch for aggressive cupping and 93 @ 5450 seems possible on paper. Now will the boat run that with the power he's got???? Seems pretty fast. I know I guy with the exact same setup in a Rage and the best he's gotten is 86. With 7 lbs of boost and CMI's he's making around 675-700 HP.

xcpilot....

Is your speedo a GPS??

Have you verified your speed using 2 GPS's to make sure they are calibrated??

My Lavorsi analog GPS actually reads 1.5 mph slower at above 90 mph than my two digital GPS's and my calibrated radar gun.

By two or more witnesses shall all truth be established.

Chris

My slip has always been ~17%. Before & after lab.

Interesting. I've set up several Rages and they all come out under 14% slip using stock props. A 496 HO usually comes stock with a 26 Bravo 1 prop. With 17% slip that works out to 68 MPH at 5000 RPM. We all know an HO Rage runs low to mid 70's stock. My Rage runs 70 at 5000 RPM (on a scan tool) with a 26" Bravo 1 in hot weather, 72-73 at 4800 with 28Bravo 1 in cool weather. Another Rage I set up ran 80 with a 26" Bravo 1 at 5600 RPM (13% slip), It ran upper 90's after a blower addition with stock 30" at 5800-5900 RPM(13% slip). So, I'm a bit confused with you guys seeing so much slip with a Rage. Of course once you start labbing and modifying props all bets are off on calculating slip.

Bobl,

My boat usually runs 15%-16% slip using Bravo's & 12%-13% using P5x's.

I believe they are using Bravo props.

The faster the boat is going with the outdrive depth being the same ... the less boat and outdrive/prop there is in the water... therefore increased slip.

The 130mph+ Howard Bullett ran slip numbers in the 18%-20% range at top speed.

I'm beginning to value slip numbers less and less, and look at overall speed and boat handling more and more.
Who the heck cares what the slip percentage is if it is indeed the fastest prop for your boat, and speed is what you are after.

Chris

That was my thought. As mph goes up, boat gets higher, lighter, more prop out of the water & increased slip. Spring I'll try 3500 rpm vs 5500 rpm & compare slip % to test the theory.

Wow! Got a few people shook up. Was not my intent. Time I think to look at a few quotes. Perhaps a bit of sober thought.

[QUOTE=CB-BLR;2988040]Somewhere the math is off...
at 29 pitch.. which is what a 30 is stock.. slip is at 6.7%
at 30 pitch .. slip is at a little over 9%

It is hard to believe that a Bravo prop has slip that low ... Hmmm

Anyway... I agree with Steve... demo a Hydromotive 30 P5x. Hydromotive has a demo program. Going up 1 inch in the hydromotives pitch will reduce rpm aproximately 150-170 rpm.

That is my favorite all-around prop.

I regularly spin a labbed 30 p5x at 5600 rpm to 92.8 mph which equals about 12.2% slip

Here's one that's interesting.

[QUOTE=CB-BLR;2992996]Bobl,

My boat usually runs 15%-16% slip using Bravo's & 12%-13% using P5x's.

I believe they are using Bravo props.

The faster the boat is going with the outdrive depth being the same ... the less boat and outdrive/prop there is in the water... therefore increased slip.

Here's another.

Here's another.

Little bit of math. 5500 rpm on a 30 pitch equals 90.6 mph with Bob's 13% slip. This does NOT include anything for cupping-or anything else! Of course my slip would be higher than a 28' much heavier Heat with a shorter drive (12%). Still trying to figure out why I am a liar and no one questions how some get to 93mph with 28 footers that are 10mph slower than 25's.

Last day on the lake I went back to the prop shop and got the 31 P5X five blade Hydromotive to re test. It worked very well and I bought it that day. I was able to spin it 5300 rpms on glass water and the acceleration was pretty good. Thinking my slip number should be down 3% at least with the 5 blade (to like 9%) compared to the Bravo4 according to CB so my speed should be pretty good. I'll let him come up with some math to keep my speed down to maybe 89. Gotta be a way for a 25 with a deeper drive to have a bigger slip than a 28 with a shorter drive.

Any one that knows me, knows I'm a stickler(sp) for data and accuracy. I make my living doing this. One thing I've learned from talking with all these folks around the country. Weather and water conditions make huge differences. So, trying to compare Chris's, Steve's and my numbers doesn't always work. I've run on Lake Cumberland (where Steve boats a lot) and seen speeds 3-4 MPH faster than I ever saw at my home lake.

I've set up and run quite a few Rage's and Heats. I know those boats very well. You are correct that you cannot compare the 2 boats. The Rage is about 8 mph faster than the Heat and runs much less prop slip with all else being equal. Just my 2 cents worth.

I've tried my best to show that your numbers are indeed mathematically possible. However would you please clarify if that speed is on GPS or not. With the HP you're running, 93 is an exceptional speed based on my experience. Also, where are you boating and what kind of weather conditions?

I've never run a P5X on a Rage. I'm guessing a 31 at 5300 would still be around 93 +/-. My Heat spun a 29 P5X at 6200 and 95 mph. What did you think about the P5X on the Rage?

Bob

Here's an intersting quote...
Lets see a pic :drink:

XPILOT,
No one's calling anyone a liar, we're just interested in how we can get that same performance with equal or more hp & why our #'s are so much different. If I had enough time, money & the perfect setup, the math says I could go 100. That would be sweet (& scary).
Even if there's a margin of error, your boat is running awsome!

I'm not making any more speed claims as you can see from my last post. I'm tired of getting this :bsflag:

I will stick to pitches and rpms, some people seem to be offended if I approach their claimed speeds. Garmin BTW to answer your question. Since I am in Canada and the boat is sleeping in Havasu there will be no testing in the near future. That may come as a relief to some. :party-smiley-004:

I for one am very interested in your numbers. Have you had your engine dyno'd? It seems you're making some really good power. It'd be real interesting to know what it's making.

Hey Dave (NordicFlame), you have a buddy with a Rage that you've driven some. If my memory serves me you said it ran 75 with a stock HO. What prop and RPM did it run? I'm assuming a 28" Bravo. Interstingly Nordic ships most midcabin Rages with a 26" prop from the factory. Maybe the closed bows are that much faster. Always trying to gather information...LOL

xcpilot,

No one is calling you a liar... we just want to see GPS backup of your claims... a pictue of the GPS or a video of you going that fast would be great...
Then the rest of us could share in your joy, and ask all sorts of fun questions on your setup. We all want to make our boats faster and faster.

It took a darn long time for you to respond to several questions about wheather you used a GPS or not... that lead many of us to doubt the validity of your claims.

Its all good... I am glad you are enjoying your boat, and having fun making upgrades... Sounds like it is a rocket ship.

Chris

P.S. Many on here doubted my claims that I had gotten my open bow Heat over 90mph with just 730HP until I provided GPS verification in the form of a picture. Many others doubted Raytart had gotten his 525 Heat to 81mph, untill he provided pictures of his GPS and a video. Don't feel like anyone is picking on you personally... its just how the game is played. When you make speed claims...back it up with GPS photo's or a video.

On a side note...

I am not sure which boat, the Rage or the Heat, is faster on the top end. The Rage is for sure quicker. This is why I say this:

The fastest Rage I have seen went 114.6 mph with 1450hp from a twin turboed 572. The boat was very unstable at these speeds... but once in a while he would get it all together.

The fastest Heat I have seen went 111 mph with 1250 hp from a quad-rotor on top of a 598. This boat was rock solid at these speeds.

I think if this Heat had 1450 horsepower, it would top the 114mph speed set by the Rage.

I would REALLY like to be the one to find out some day. :evilb:

598 with a 5.0 Whipple... Dustin and Eddie Young say 1450 hp on pump gas!

Some day!

Chris

I have a new old Hill bro 32


I also have a mach 32 4 blade,like new
http://s35.photobucket.com/albums/d156/Hustler388/

make offers

Very good :lolhit:

Chris

Point taken. However, I think you need to be more focused when you state your case. You talk about which boat (Rage or Heat) is faster, but what you really mean is which hull is faster with unlimited horsepower (ie 1500hp). Most people would think in terms of which hull is faster with power that might likely be installed in either hull-ie 496HO, 525, 600SC etc. If you power up both hulls to infinity it goes without saying that at some point the smaller one will be less stable and harder to drive than the larger one. Having said that, it appears even using your research that Rages are faster, at least until you power your Heat up to 1500hp. I doubt you would want to compare a Heat and Rage using real world power like 496's or 525's where both hulls can reach top speed and are not limited by stability issues. Just trying to put things out there without my own personal spin.

Terry